With the rapid development of business information dissemination services, a variety of outdoor information display devices such as billboards have become a public infrastructure. The prior art outdoor information display devices are found in a variety of styles and have relatively wide applications. A common example of an outdoor information display device may be a single-sided or double-sided billboard resembling an anti-aircraft gun that is fixedly installed on the roadside, which however can provide relatively small effective advertising space and can be static and dull. Another example could be a trivision billboard rotated by motor-driven rollers. This type of billboards can increase the amount of information presented in the same advertising space and can cyclically switch between several advertisements. However, they can only be viewed from one direction, which means a very limited viewing angle. In addition, these rotary billboards rely on external power supplies, and in high winds they may experience extremely large impacts and so could be easily damaged.
Existing outdoor LED matrix display billboards employ a controller to control the ON/OFF or color of an LED at each position of the square fixedly set LED matrix panel to produce a variety of dynamic graphic and textual information. But a large number of LEDs would be required, resulting in high overall energy consumption and high operation and management costs. Moreover, they can only provide a fixed viewing angle of around 150°, so that a full 360° viewing angle is not allowed.
Wind is one of the most common clean energy sources in nature, and wind power is also a conventional technology. However, it is less common to combine wind power with equipment such as outdoor billboards to exploit the wind to directly drive the rotation of large outdoor billboards and also provide electric energy for the billboards. To generate power from the wind, the billboard needs to spin fast, but on a fast spinning billboard the advertising (graphic and textual) information would become blurred so that it would be awkward for an observer at a fixed position under the billboard to make out the contents displayed thereon.
Therefore, in the prior art where the wind is used to drive the billboard for power generation, the information would be unable to be clearly displayed on the billboard. In particular, the natural wind is often unsteady and noncontinuous, hence resulting in a changing rotational speed of the billboard and also an unstable information presentation on the billboard that is driven by the wind. On the other hand, if people wish to see clearly the contents on the billboards, then the information carrier presented on the billboard must be kept stable. These all are problems not yet overcome by the prior art.